AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Long-Term Trend Analysis of Factors Contributing to PM2.5 in Toronto: What is this Elemental Carbon-Rich Factor?
CHEOL-HEON JEONG, Greg J. Evans, Dennis Herod, Ewa Dabek-Zlotorzynska, SOCAAR, University of Toronto
Abstract Number: 598 Working Group: Source Apportionment
Abstract A previous source apportionment study of five Canadian cities using Positive Matrix Factorization (PMF) revealed an elemental carbon (EC)-rich factor, characterized by more thermally stable EC fractions, that was only present at the three sites in south-eastern Canada (Jeong et al., 2011). A follow-up study of five urban and rural sites across this 600 km region showed that this EC-rich factor exhibited similar temporal patterns at the both the urban and rural sites, with an increasing trend from 2005 (Jeong et al., 2013). On average, the EC-rich factor accounted for approximately 50% of the total EC and contributed 6~20% of the total PM2.5 mass concentrations in this region. A third source apportionment study was conducted using long-term PM2.5 chemical speciation data measured from 2004 to 2011 in Toronto to investigate the underlying causes for the reduction in PM2.5 mass that has occurred since 2005. The contributions of PMF-resolved factors associated with long-range transport, i.e., secondary sulphate and secondary nitrate factors were found to show similar decreasing trends. This finding suggests that a reduction of coal combustion may be the main reason for the PM2.5 improvement in this urban area. The 8-year trend of the EC-rich factor contribution will be discussed in detail and the characteristic of the factor will be presented.
Jeong et al. (2011) Atmos. Poll. Res. 2, 158-171.
Jeong et al. (2013) Environ. Sci. Technol. submitted.